1. Technical Field
The present invention pertains to safety valves useful to control flow in well conduits. This invention pertains to a safety valve, particularly useful in gas storage systems, which automatically closes when production mass flow reaches a predetermined rate at a particular ambient pressure.
2. Background Information
A considerable number of pressure-differential type safety valves are known for wells, which are direct-controlled, i.e., actuated, to close because fluid flow through generates differential pressure and sufficient closing force in these valves. An example of a direct-controlled (or flow actuated) safety valve is shown on page 142 of "Otis Products and Services" (OEC 5516), a September, 1989 publication of Otis Engineering Corporation, Belt Line at Webbs Chapel Roads, P.O. Box 819052, Dallas, Tex. 75381-9052. Another example of a direct-controlled safety valve is shown in application Ser. No. 07/699,368, filed in the United States Patent and Trademark Office May 13, 1991, for applicants William W. Dollison and John C. Gano.
Other examples of flow actuated safety valves are shown in the following U.S. Patents. U.S. Pat. No. 4,708,163 to Deaton discloses a valve which compares pressure of fluid flowing through the valve to pressure exterior of the valve. If the differential pressure exceeds a predetermined value, a pressure sensitive bellows is actuated to close the valve.
U.S. Pat. No. 4,664,195 to Deaton covers another direct acting (controlled) safety valve. If the rate of change of fluid pressure flowing through this valve exceeds a preselected value, a pressure sensitive piston will close the valve.
U.S. Pat. No. 4,339,001 to Paschal, Jr., is for a differential operated safety valve which is held open until the difference in pressure between fluid in a chamber inside the valve and fluid flowing through the valve exceeds a preselected value causing the valve to close.
U.S. Pat. No. 3,881,511 to Dollison discloses a well safety valve utilizing a poppet type valve which is actuated to close when the flow rate through the valve induces sufficient pressure differential in the valve to actuate the valve to close.
Inventor Phillip S. Sizer utilizes a ball type valve in the safety valve structure of U.S. Pat. No. 3,236,255. The ball valve is rotated to close in one form of the safety valve when the pressure above the ball valve drops below a predetermined value and in another form when the flowing pressure differential across the ball valve exceeds a predetermined value.
U.S. Pat. No. 3,070,119 to G. M. Raulins shows another direct controlled safety valve structure which is actuated to close when a predetermined value of differential flowing pressure below and above an orifice is reached.
All previously noted patents are incorporated herein for reference.